Proton exchange membrane (PEM) fuel cells have attributes that make them attractive for vehicle applications. In order to regulate the temperature of the fuel cell, all of the excess heat in the coolant flowing from the fuel cell must be rejected through the radiator of the vehicle. Continuous rejection of a certain quantity of heat at a lower temperature takes a larger radiator than rejection of the same quantity of heat at a higher temperature. PEM fuel cells typically operate between 65° C. and 80° C.; this relatively low operating temperature requires that unduly large radiators must be used in the vehicles.
Membranes which are meant to operate at about 120° C. are under development. However, platinum solubility increases with temperature, and the rate of carbon corrosion increases exponentially with temperature. Therefore, degradation of the cathode catalyst and carbon support will occur more quickly at the higher temperatures.